<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .pink {
            background-color: pink;
        }
    </style>
</head>
<body>
<button class="pink">按钮1</button>
<button>按钮2</button>
<button>按钮3</button>
<button>按钮4</button>


<script>
    const buttons = document.querySelectorAll("button");
    for (let i = 0; i < buttons.length; i++) {
        buttons[i].addEventListener('click', function () {
            document.querySelector(".pink").className = ""
            this.className = 'pink'
        })
    }
</script>
</body>
</html>